The de-Broglie wavelength of a free electron with kinetic energy 'E' is $ \lambda$. If the kinetic energy of the electron is doubled, the de-Broglie wavelength is

Question

$\begin {array} {1 1} (1)\;\large\frac{\lambda}{\sqrt 2} & \quad (2)\;\sqrt 2 \lambda \\ (3)\;\large\frac{\lambda}{2} & \quad (4)\;2\lambda \end {array}$